.containera {
  
  position: relative;
  
}

.overlaya {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  opacity: 0.5;
  background-color: #FDFEFE  ;
  overflow: hidden;
  width: 0;
  height: 94%;
  transition: .5s ease;
}

.containera:hover .overlaya {
  
  width: 86%;
}